1. Field of the Invention
Exemplary embodiments of the present invention relate to a wireless communication system; and, more particularly, to a small antenna which controls a resonant frequency using a split ring resonator (hereafter, referred to as SRR) structure in a wireless communication system, and a method for manufacturing the same.
2. Description of Related Art
In order to transmit and receive signals in a wireless communication system, various types of antennas have been proposed. The antennas are essential components in a wireless communication system for transmitting and receiving electromagnetic wave signals, and resonate at a specific frequency of electromagnetic wave to transmit and receive an electromagnetic wave signal of the corresponding frequency. Recently, as the wireless communication system has rapidly developed, the antennas have been not only used in various manners, but have also been reduced in size.
In general, however, since a small antenna has a large reactance component and a very small radiation resistance value, it is difficult to accomplish impedance matching. Accordingly, since the small antenna has a very narrow impedance bandwidth and low efficiency, it exhibits a low gain characteristic. In order to accomplish the impedance matching of the small antenna, an additional matching network is required in an antenna feed unit. This may increase the cost and time as well as the complexity when the small antenna is implemented. Furthermore, when the additional matching network is provided for the impedance matching of the small antenna, a resistance loss may occur because the additional matching network is included in a matching circuit of the small antenna. The resistance loss may reduce the efficiency of the small antenna, and the additional matching network may increase the entire size of the small antenna.
For example, a general small antenna has a primary-mode resonant structure and an electrical length of half a wavelength with respect to a wavelength corresponding to a resonant frequency. Accordingly, when an electromagnetic wave guided along a wire in the small antenna forms a standing wave in the wire, resonance occurs. At this time, since the electrical length of the small antenna is decided depending on the resonant frequency, the size of the small antenna having the primary-mode resonant structure is changed in accordance with the resonant frequency. In particular, as the operation frequency decreases, the size of the small antenna may increase. To solve such a problem, a meander antenna has been proposed. However, the length of the meander antenna is also decided by the resonant frequency. Therefore, as the antenna is reduced in size, the complexity of the antenna inevitably increases. That is because the antenna having a fixed length should be formed in a limited small space.
Therefore, there is demand for a method for implementing a small antenna, which may easily accomplish the impedance matching without an additional matching network for the impedance matching of the small antenna, minimize the size and the implementation cost and time as well as the complexity of the antenna, and increase the antenna efficiency.